How can I do conditional sort on Gremlin/Neptune-CodePudding

I am trying to build a query that will return a Vertex both edges, and sort them conditionally by value of a different property according to whether the original Vertex is the out Vertex or in Vertex in the given edge, I have two properties that will comply with this sort ("origin_pinned" & "target_pinned"), if an edge in Vertex is the original vertex I want to use "origin_pinned" value if its the out vertex then I want to use "target_pinned" value

This must be one query

I tried to run the following query but does not seem to have effect:

g.V('id123').bothE().order().by(values(choose(inV().is(V('id123')), 
constant('origin_pinned'), constant('target_pinned'))), desc)

CodePudding user response：

The values step will not work the way you are trying to use it. You did not include any sample data in the question, but using the air-routes data set, the query can most likely be simplified as shown below:

gremlin> g.V(44).as('a').
......1>   bothE().
......2>   order().
......3>     by(coalesce(
......4>         where(inV().as('a')).constant('origin_pinned'),
......5>         constant('target_pinned')))

==>e[57948][3742-contains->44]
==>e[54446][3728-contains->44]
==>e[4198][13-route->44]
==>e[4776][31-route->44]
==>e[4427][20-route->44]
==>e[4015][8-route->44]
==>e[5061][44-route->8]
==>e[5062][44-route->13]
==>e[5063][44-route->20]
==>e[5064][44-route->31]

and to prove the reverse also works

gremlin> g.V(44).as('a').
......1>   bothE().
......2>   order().
......3>     by(coalesce(
......4>         where(outV().as('a')).constant('origin_pinned'),
......5>         constant('target_pinned')))

==>e[5061][44-route->8]
==>e[5062][44-route->13]
==>e[5063][44-route->20]
==>e[5064][44-route->31]
==>e[57948][3742-contains->44]
==>e[54446][3728-contains->44]
==>e[4198][13-route->44]
==>e[4776][31-route->44]
==>e[4427][20-route->44]
==>e[4015][8-route->44]

To check things are working as expected, we can do:

gremlin> g.V(44).as('a').
......1>   bothE().as('e').
......2>   coalesce(
......3>     where(inV().as('a')).constant('origin_pinned'),
......4>     constant('target_pinned')).as('p').
......5>     order().
......6>   select('e','p')

==>[e:e[57948][3742-contains->44],p:origin_pinned]
==>[e:e[54446][3728-contains->44],p:origin_pinned]
==>[e:e[4198][13-route->44],p:origin_pinned]
==>[e:e[4776][31-route->44],p:origin_pinned]
==>[e:e[4427][20-route->44],p:origin_pinned]
==>[e:e[4015][8-route->44],p:origin_pinned]
==>[e:e[5061][44-route->8],p:target_pinned]
==>[e:e[5062][44-route->13],p:target_pinned]
==>[e:e[5063][44-route->20],p:target_pinned]
==>[e:e[5064][44-route->31],p:target_pinned]

CodePudding user response：

managed to figure it out with the help of Kelvin Lawrence's answer:

g.V('id123').as('a').bothE().order().by(
coalesce(
where(
outV().as('a')).values('origin_pinned'),
values('target_pinned'), 
constant(0)), 
desc)